MapMultiPolygon

MapControl/Shared/PolygonCollection.cs

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+// XAML Map Control - https://github.com/ClemensFischer/XAML-Map-Control
+// Copyright © 2024 Clemens Fischer
+// Licensed under the Microsoft Public License (Ms-PL)
+
+using System;
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using System.Collections.Specialized;
+using System.Linq;
+
+namespace MapControl
+{
+    /// <summary>
+    /// An ObservableCollection of IEnumerable of Location. PolygonCollection adds a CollectionChanged
+    /// listener to each element that implements INotifyCollectionChanged and, when such an element changes,
+    /// fires its own CollectionChanged event with NotifyCollectionChangedAction.Replace for that element.
+    /// </summary>
+    public class PolygonCollection : ObservableCollection<IEnumerable<Location>>
+    {
+        private void PolygonChanged(object sender, NotifyCollectionChangedEventArgs e)
+        {
+            OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Replace, sender, sender));
+        }
+
+        protected override void InsertItem(int index, IEnumerable<Location> polygon)
+        {
+            if (polygon is INotifyCollectionChanged addedPolygon)
+            {
+                addedPolygon.CollectionChanged += PolygonChanged;
+            }
+
+            base.InsertItem(index, polygon);
+        }
+
+        protected override void SetItem(int index, IEnumerable<Location> polygon)
+        {
+            if (this[index] is INotifyCollectionChanged removedPolygon)
+            {
+                removedPolygon.CollectionChanged -= PolygonChanged;
+            }
+
+            if (polygon is INotifyCollectionChanged addedPolygon)
+            {
+                addedPolygon.CollectionChanged += PolygonChanged;
+            }
+
+            base.SetItem(index, polygon);
+        }
+
+        protected override void RemoveItem(int index)
+        {
+            if (this[index] is INotifyCollectionChanged removedPolygon)
+            {
+                removedPolygon.CollectionChanged -= PolygonChanged;
+            }
+
+            base.RemoveItem(index);
+        }
+
+        protected override void ClearItems()
+        {
+            foreach (var polygon in this.OfType<INotifyCollectionChanged>())
+            {
+                polygon.CollectionChanged -= PolygonChanged;
+            }
+
+            base.ClearItems();
+        }
+    }
+}